Introduction
Transrectal ultrasound-guided prostate biopsy (TRUS-Bx) is the standard procedure for diagnosing prostate cancer, with over a million procedures performed annually worldwide [1,2]. Despite its diagnostic importance, TRUS-Bx carries the risk of infectious complications, including prostatitis, bacteremia, and sepsis, largely due to bacterial translocation from the rectum during the procedure. Escherichia coli (E. coli) is the most common causative pathogen [2,3].
To reduce infection risk, prophylactic antibiotics, most notably fluoroquinolones and cephalosporins, are routinely administered [4,5]. However, recent studies have reported persistent post-biopsy infections and a significant increase in fluoroquinolone-resistant E. coli [6,7]. Overuse of broad-spectrum antibiotics has contributed to multidrug-resistant (MDR) strains, complicating treatment and increasing healthcare burdens [8-10].
Even with prophylactic antibiotics, the rectal mucosa remains a reservoir for resistant bacteria [11]. Therefore, non-antibiotic preventive strategies have been explored [12]. Among these, povidone-iodine rectal cleansing has emerged as a promising adjunctive method to reduce rectal bacterial load before biopsy [13]. As a broad-spectrum antiseptic, povidone-iodine may enhance the efficacy of antibiotics and mitigate colonization by MDR organisms. However, there is limited evidence on the additive effect of povidone-iodine cleansing combined with cephalosporin prophylaxis [14-16].
Given the increased risk of antimicrobial resistance and persistence of infection risk despite antibiotic use, this study aimed to evaluate whether combining povidone-iodine rectal cleansing with cephalosporin prophylaxis reduces infectious complications after TRUS-Bx more effectively than cephalosporin monotherapy.
Methods
Study population
This retrospective study was approved by the Institutional Review Board of Keimyung University Dongsan Hospital (IRB No. 2024-10-035). The requirement for obtaining informed consent was waived by the board due to the retrospective nature of the study. We reviewed the medical records of 2,514 patients who underwent TRUS-Bx between January 2018 and December 2023. After excluding 396 patients due to incomplete documentation regarding povidone-iodine cleansing or the use of non-cephalosporin antibiotics, 2,118 patients were included. Patients were categorized into groups based on whether povidone-iodine rectal cleansing was part of the institutional protocol at the time of their procedure, as the group assignment was not randomized.
The participants were categorized into two groups: Group I (n = 682) received only prophylactic cephalosporins, and Group II (n = 1,436) received the same antibiotic prophylaxis plus rectal cleansing with povidone-iodine. Indications for biopsy included prostate-specific antigen (PSA) levels of > 3 ng/mL and/or abnormal findings on digital rectal examination. Age, PSA levels, prostate volume, number of biopsy cores, comorbidities, and biopsy results were compared between the two groups. All patients underwent prebiopsy urinalysis and urine cultures, with no significant differences in baseline pyuria or bacteriuria between the two groups.
Prophylactic antibiotics and biopsy methods
All patients received sodium phosphate or glycerin enemas 1–2 hours before biopsy. The procedure was performed with the patient in the left lateral decubitus position. Group I received intravenous prophylactic cephalosporin (cefotetan or flomoxef, 1 g) 30 minutes before the procedure, followed by oral cefprozil 200 mg twice daily for 5 days after the biopsy. Group II additionally underwent rectal cleansing with 10 mL of 0.1% povidone-iodine both before and after the biopsy. Rectal cleansing was performed by instilling 10 mL of 0.1% povidone-iodine into the rectum using a syringe before and after the biopsy, with a retention time of 2–3 minutes.
Biopsy guidance was performed using a HITACHI ARIETTA 850 ultrasound system (Hitachi Ltd., Tokyo, Japan) and an 18-gauge core needle, either a BARD Max-Core (C. R. Bard, Inc., Covington, GA, USA) or a Vescut automatic biopsy needle (Geotek Medical, Ankara, Turkey). A standard 12-core protocol was used, and additional samples were collected if sonographic abnormalities were noted. Four experienced urologists performed all the procedures. Follow-up evaluations, including urinalysis and symptom review, were conducted within 14 days after biopsy. The patients were advised to visit the emergency department if any complications developed.
Post-biopsy complications
Infectious complications within 7 days after biopsy included fever (≥ 38°C), urinary tract infection (UTI), acute prostatitis, bacteremia, and sepsis. Acute prostatitis was analyzed separately in this study because of its distinct clinical severity, treatment implications, and relevance to post-biopsy risk stratification. UTI was defined as bacteriuria ≥ 105 CFU/mL with urinary symptoms. Acute prostatitis was diagnosed based on fever, pelvic discomfort, lower urinary tract symptoms, and prostatic tenderness. Bacteremia was confirmed by positive blood cultures in symptomatic patients. Sepsis was defined using Sepsis-3 criteria as an acute rise of ≥ 2 points in the Sequential Organ Failure Assessment score, and septic shock as hypotension requiring vasopressors with lactate levels of ≥ 2 mmol/L despite adequate fluid resuscitation [17].
Statistical methods
Group comparisons were performed using independent t-tests or Mann–Whitney U tests, and categorical variables were analyzed using chi-squared or Fisher’s exact tests. Infectious outcomes were evaluated using the chi-squared test. Statistical significance was set at p < 0.05. All analyses were performed using IBM SPSS Statistics version 29.0.0 (IBM Corp.).
Results
Table 1 shows the comparison of baseline characteristics between Groups I and II. There were no significant differences in age, PSA levels, prostate volume, or biopsy results between the groups. However, Group II had a higher number of biopsy cores compared to Group I (12.5 ± 1.9 vs. 12.1 ± 1.9, p = 0.003). Hypertension (HTN) and diabetes mellitus (DM) were more prevalent in Group II (HTN: 43.7% vs. 28.7%, p < 0.001; DM: 20.5% vs. 12.6%, p < 0.001). No immediate or delayed adverse events associated with povidone-iodine rectal cleansing were observed during follow-up.
Group I showed significantly higher rates of post-biopsy infectious complications (Fig. 1). Acute prostatitis occurred in 1.2% of Group I patients and 0.3% of Group II patients (p = 0.028). Bacteremia (0.6% vs. 0.1%, p = 0.040) and fever (0.9% vs. 0.2 %, p = 0.036) were also more common in Group I. Sepsis and complications within four weeks were numerically higher in Group I, but did not reach statistical significance (sepsis: 0.3% vs. 0.1%, p = 0.244; complications within 4 weeks: 0.9% vs. 0.3%, p = 0.191; Table 2).
Hospitalization due to infectious complications occurred in 0.9% and 0.4% of the patients in Groups I and II, respectively (Table 3). Among these, Extended-Spectrum Beta-Lactamase (ESBL)-producing E. coli was isolated from urine cultures in 83.3% of patients in Group I and 20.0% in Group II (p = 0.080) and from blood cultures in 66.7% and 0% of patients in Groups I and II, respectively (p = 0.061). The isolation rate of Pseudomonas aeruginosa was low and was not significantly different between the two groups.
Discussion
This study demonstrated that combining povidone-iodine rectal cleansing with cephalosporin prophylaxis significantly reduces infectious complications, including fever, acute prostatitis, and bacteremia, following TRUS-Bx. This benefit was particularly notable in the reduction of acute prostatitis and bacteremia, which represent more serious complications with higher morbidities.
The rationale for rectal disinfection is to reduce the rectal bacterial load before the transrectal procedure, thereby decreasing the risk of bacterial translocation. Previous studies have shown that despite adequate antibiotic prophylaxis, the rectal mucosa remains a reservoir for MDR bacteria, particularly E. coli, which is the most implicated organism in post-TRUS-Bx infections [2,8,9]. Given the increasing resistance to fluoroquinolones, cephalosporins are now frequently used as first-line prophylaxis [4,10,11]. However, even with cephalosporin use, infection risks persist, necessitating adjunctive preventive strategies [9,18-20].
Our findings align with those of previous research, suggesting that intrarectal povidone-iodine cleansing can significantly reduce infectious complications. For example, Cadilhe [21] and Abughos et al. [22] demonstrated the efficacy of povidone-iodine when applied as a rectal suppository or lavage before biopsy. In our study, a simple 0.1% povidone-iodine solution was used for rectal cleansing immediately before and after biopsy without prostate massage, and it still showed significant protective effects. This finding supports the practicality and effectiveness of this approach in real-world clinical settings.
The observed reduction in the isolation of ESBL-producing E. coli in Group II suggests a potential role for rectal disinfection in mitigating colonization by MDR organisms. Although statistical significance was not reached for ESBL-related outcomes, this trend was consistent with existing literature [13,14,23]. Notably, ESBL-producing E. coli was isolated from 83.3% of the infected patients in Group I compared to 20.0% in Group II. Although the sample size for these sub-analyses was small, the clinical implications are relevant. Reducing the rectal burden of resistant bacteria may lower the risk of breakthrough infections that are more difficult to treat.
Our study reaffirms the effectiveness of cephalosporins and highlights that antibiotic prophylaxis alone may not be sufficient, especially in the era of increasing antimicrobial resistance. Rectal disinfection provides a non-antibiotic adjunct that can reduce reliance on broad-spectrum agents and slow the development of resistance. This is in line with meta-analyses recommending non-antibiotic preventive measures as part of infection control in TRUS-Bx [12,24].
Interestingly, although Group II had a significantly higher mean number of biopsy cores and a greater prevalence of comorbidities, such as HTN and DM, this group exhibited significantly fewer infections. This is particularly notable given that both an increased biopsy core number and the presence of comorbidities such as DM and HTN are well-established risk factors for post-biopsy infections [7]. This finding underscores the robustness of povidone-iodine rectal cleansing in mitigating infection risk, even among patients who are typically considered at high risk. Similar results have been reported in other studies, which also demonstrated a significant reduction in post-biopsy infections among patients who underwent povidone-iodine disinfection [15,25-28]. These findings support the role of rectal disinfection as an essential adjunctive measure in routine TRUS-Bx protocols, particularly in high-risk populations.
Pradere et al.’s [24] meta-analysis pooled data from numerous studies, including those with large sample sizes and real-world clinical designs, thereby supporting the effectiveness of povidone-iodine cleansing. Nonetheless, some limitations of this study must be acknowledged. The retrospective design introduced a potential selection bias, particularly with the exclusion of patients with undocumented disinfection status. The Clavien–Dindo classification could not be applied due to the retrospective nature of the study and the lack of sufficient granularity in medical record documentation regarding complication severity. Additionally, differences in comorbidities, such as DM and HTN, may have influenced the outcomes despite statistical adjustment. Furthermore, procedural variations among the operators, including biopsy techniques and patient preparation, were not controlled.
Another limitation is the lack of long-term follow-up data. While early post-biopsy infections (within 7 days) were well documented, delayed infections, persistent bacteriuria, or long-term complications were not assessed. Although no adverse effects related to povidone-iodine cleansing were observed, the long-term safety and patient tolerability of this approach require further validation.
Given its ease of implementation, low cost, and the absence of observed side effects, povidone-iodine rectal cleansing is a promising adjunct to antibiotic prophylaxis for TRUS-Bx. Our findings support its adoption in standard prebiopsy protocols, particularly in high-risk populations. Future multicenter, prospective studies are warranted to determine the optimal concentration, volume, and timing of disinfection, as well as to compare its efficacy with other emerging strategies such as formalin needle disinfection or targeted antibiotic prophylaxis based on rectal swabs [20,28].
In conclusion, our findings demonstrate that povidone-iodine rectal cleansing, when used alongside cephalosporin prophylaxis, significantly reduced the incidence of fever, acute prostatitis, and bacteremia after TRUS-Bx. In the context of increasing antimicrobial resistance and limited antibiotic options, this simple and low-cost adjunctive measure offers a practical solution for enhancing infection prevention. Given its safety profile, ease of use, and clinical benefits, povidone-iodine rectal cleansing should be considered a standard component of pre-biopsy preparations, especially in patients at an elevated risk of infectious complications.
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